International law is the collection of rules that define the legal responsibilities of States in their relations with one another and the treatment of individuals within State boundaries. Its domain encompasses a broad range of issues of international concern, including human rights, disarmament, international crime, refugees, migration and problems of nationality, the use of force, and the conduct of war. It also regulates the global commons, such as the environment and sustainable development, international waters, outer space and world trade.

Unlike domestic or local law, international law is not set down in legislation approved by parliaments; it is largely created by consent—agreements, conventions and treaties signed and ratified by sovereign States. This makes it more difficult to determine the precise rules of international law than domestic or national laws.

In general, the development of international law is a primary goal of the United Nations. This is done by its specialized agencies, such as the International Court of Justice (ICJ), and its multilateral negotiating bodies, as well as through its regional commissions and inter-governmental organizations.

However, there is no generally accepted coercive authority that binds sovereign States to a body of international law. Rather, compliance with international law is based on an incentive principle: States comply with public international law norms because they recognize the value that this system of rules provides to them by providing them with a framework, a set of methods and mechanisms for interacting internationally and a common conceptual language.